/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the  "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
/*
 * $Id$
 */
package wx.xml.xalan.xml.utils;

import java.io.IOException;
import java.io.Serializable;

import wx.xml.xalan.xml.res.XMLErrorResources;
import wx.xml.xalan.xml.res.XMLMessages;

/**
 * A class to represent a Uniform Resource Identifier (URI). This class
 * is designed to handle the parsing of URIs and provide access to
 * the various components (scheme, host, port, userinfo, path, query
 * string and fragment) that may constitute a URI.
 * <p>
 * Parsing of a URI specification is done according to the URI
 * syntax described in RFC 2396
 * <http://www.ietf.org/rfc/rfc2396.txt?number=2396>. Every URI consists
 * of a scheme, followed by a colon (':'), followed by a scheme-specific
 * part. For URIs that follow the "generic URI" syntax, the scheme-
 * specific part begins with two slashes ("//") and may be followed
 * by an authority segment (comprised of user information, host, and
 * port), path segment, query segment and fragment. Note that RFC 2396
 * no longer specifies the use of the parameters segment and excludes
 * the "user:password" syntax as part of the authority segment. If
 * "user:password" appears in a URI, the entire user/password string
 * is stored as userinfo.
 * <p>
 * For URIs that do not follow the "generic URI" syntax (e.g. mailto),
 * the entire scheme-specific part is treated as the "path" portion
 * of the URI.
 * <p>
 * Note that, unlike the java.net.URL class, this class does not provide
 * any built-in network access functionality nor does it provide any
 * scheme-specific functionality (for example, it does not know a
 * default port for a specific scheme). Rather, it only knows the
 * grammar and basic set of operations that can be applied to a URI.
 */
public class URI implements Serializable {
    static final long serialVersionUID = 7096266377907081897L;
    /**
     * reserved characters
     */
    private static final String RESERVED_CHARACTERS = ";/?:@&=+$,";
    /**
     * URI punctuation mark characters - these, combined with
     * alphanumerics, constitute the "unreserved" characters
     */
    private static final String MARK_CHARACTERS = "-_.!~*'() ";
    /**
     * scheme can be composed of alphanumerics and these characters
     */
    private static final String SCHEME_CHARACTERS = "+-.";
    /**
     * userinfo can be composed of unreserved, escaped and these
     * characters
     */
    private static final String USERINFO_CHARACTERS = ";:&=+$,";
    /**
     * Indicate whether in DEBUG mode
     */
    private static boolean DEBUG = false;
    /**
     * Stores the scheme (usually the protocol) for this URI.
     *
     * @serial
     */
    private String m_scheme = null;

    /**
     * If specified, stores the userinfo for this URI; otherwise null.
     *
     * @serial
     */
    private String m_userinfo = null;

    /**
     * If specified, stores the host for this URI; otherwise null.
     *
     * @serial
     */
    private String m_host = null;

    /**
     * If specified, stores the port for this URI; otherwise -1.
     *
     * @serial
     */
    private int m_port = -1;

    /**
     * If specified, stores the path for this URI; otherwise null.
     *
     * @serial
     */
    private String m_path = null;

    /**
     * If specified, stores the query string for this URI; otherwise
     * null.
     *
     * @serial
     */
    private String m_queryString = null;

    /**
     * If specified, stores the fragment for this URI; otherwise null.
     *
     * @serial
     */
    private String m_fragment = null;

    /**
     * Construct a new and uninitialized URI.
     */
    public URI() {
    }

    /**
     * Construct a new URI from another URI. All fields for this URI are
     * set equal to the fields of the URI passed in.
     *
     * @param p_other the URI to copy (cannot be null)
     */
    public URI(URI p_other) {
        initialize(p_other);
    }

    /**
     * Construct a new URI from a URI specification string. If the
     * specification follows the "generic URI" syntax, (two slashes
     * following the first colon), the specification will be parsed
     * accordingly - setting the scheme, userinfo, host,port, path, query
     * string and fragment fields as necessary. If the specification does
     * not follow the "generic URI" syntax, the specification is parsed
     * into a scheme and scheme-specific part (stored as the path) only.
     *
     * @param p_uriSpec the URI specification string (cannot be null or
     *                  empty)
     * @throws MalformedURIException if p_uriSpec violates any syntax
     *                               rules
     */
    public URI(String p_uriSpec) throws MalformedURIException {
        this((URI) null, p_uriSpec);
    }

    /**
     * Construct a new URI from a base URI and a URI specification string.
     * The URI specification string may be a relative URI.
     *
     * @param p_base    the base URI (cannot be null if p_uriSpec is null or
     *                  empty)
     * @param p_uriSpec the URI specification string (cannot be null or
     *                  empty if p_base is null)
     * @throws MalformedURIException if p_uriSpec violates any syntax
     *                               rules
     */
    public URI(URI p_base, String p_uriSpec) throws MalformedURIException {
        initialize(p_base, p_uriSpec);
    }

    /**
     * Construct a new URI that does not follow the generic URI syntax.
     * Only the scheme and scheme-specific part (stored as the path) are
     * initialized.
     *
     * @param p_scheme             the URI scheme (cannot be null or empty)
     * @param p_schemeSpecificPart the scheme-specific part (cannot be
     *                             null or empty)
     * @throws MalformedURIException if p_scheme violates any
     *                               syntax rules
     */
    public URI(String p_scheme, String p_schemeSpecificPart)
        throws MalformedURIException {

        if (p_scheme == null || p_scheme.trim().length() == 0) {
            throw new MalformedURIException(
                "Cannot construct URI with null/empty scheme!");
        }

        if (p_schemeSpecificPart == null
            || p_schemeSpecificPart.trim().length() == 0) {
            throw new MalformedURIException(
                "Cannot construct URI with null/empty scheme-specific part!");
        }

        setScheme(p_scheme);
        setPath(p_schemeSpecificPart);
    }

    /**
     * Construct a new URI that follows the generic URI syntax from its
     * component parts. Each component is validated for syntax and some
     * basic semantic checks are performed as well.  See the individual
     * setter methods for specifics.
     *
     * @param p_scheme      the URI scheme (cannot be null or empty)
     * @param p_host        the hostname or IPv4 address for the URI
     * @param p_path        the URI path - if the path contains '?' or '#',
     *                      then the query string and/or fragment will be
     *                      set from the path; however, if the query and
     *                      fragment are specified both in the path and as
     *                      separate parameters, an exception is thrown
     * @param p_queryString the URI query string (cannot be specified
     *                      if path is null)
     * @param p_fragment    the URI fragment (cannot be specified if path
     *                      is null)
     * @throws MalformedURIException if any of the parameters violates
     *                               syntax rules or semantic rules
     */
    public URI(String p_scheme, String p_host, String p_path, String p_queryString, String p_fragment)
        throws MalformedURIException {
        this(p_scheme, null, p_host, -1, p_path, p_queryString, p_fragment);
    }

    /**
     * Construct a new URI that follows the generic URI syntax from its
     * component parts. Each component is validated for syntax and some
     * basic semantic checks are performed as well.  See the individual
     * setter methods for specifics.
     *
     * @param p_scheme      the URI scheme (cannot be null or empty)
     * @param p_userinfo    the URI userinfo (cannot be specified if host
     *                      is null)
     * @param p_host        the hostname or IPv4 address for the URI
     * @param p_port        the URI port (may be -1 for "unspecified"; cannot
     *                      be specified if host is null)
     * @param p_path        the URI path - if the path contains '?' or '#',
     *                      then the query string and/or fragment will be
     *                      set from the path; however, if the query and
     *                      fragment are specified both in the path and as
     *                      separate parameters, an exception is thrown
     * @param p_queryString the URI query string (cannot be specified
     *                      if path is null)
     * @param p_fragment    the URI fragment (cannot be specified if path
     *                      is null)
     * @throws MalformedURIException if any of the parameters violates
     *                               syntax rules or semantic rules
     */
    public URI(String p_scheme, String p_userinfo, String p_host, int p_port, String p_path, String p_queryString, String p_fragment)
        throws MalformedURIException {

        if (p_scheme == null || p_scheme.trim().length() == 0) {
            throw new MalformedURIException(XMLMessages.createXMLMessage(XMLErrorResources.ER_SCHEME_REQUIRED, null)); //"Scheme is required!");
        }

        if (p_host == null) {
            if (p_userinfo != null) {
                throw new MalformedURIException(
                    XMLMessages.createXMLMessage(XMLErrorResources.ER_NO_USERINFO_IF_NO_HOST, null)); //"Userinfo may not be specified if host is not specified!");
            }

            if (p_port != -1) {
                throw new MalformedURIException(
                    XMLMessages.createXMLMessage(XMLErrorResources.ER_NO_PORT_IF_NO_HOST, null)); //"Port may not be specified if host is not specified!");
            }
        }

        if (p_path != null) {
            if (p_path.indexOf('?') != -1 && p_queryString != null) {
                throw new MalformedURIException(
                    XMLMessages.createXMLMessage(XMLErrorResources.ER_NO_QUERY_STRING_IN_PATH, null)); //"Query string cannot be specified in path and query string!");
            }

            if (p_path.indexOf('#') != -1 && p_fragment != null) {
                throw new MalformedURIException(
                    XMLMessages.createXMLMessage(XMLErrorResources.ER_NO_FRAGMENT_STRING_IN_PATH, null)); //"Fragment cannot be specified in both the path and fragment!");
            }
        }

        setScheme(p_scheme);
        setHost(p_host);
        setPort(p_port);
        setUserinfo(p_userinfo);
        setPath(p_path);
        setQueryString(p_queryString);
        setFragment(p_fragment);
    }

    /**
     * Determine whether a scheme conforms to the rules for a scheme name.
     * A scheme is conformant if it starts with an alphanumeric, and
     * contains only alphanumerics, '+','-' and '.'.
     *
     * @param p_scheme The sheme name to check
     * @return true if the scheme is conformant, false otherwise
     */
    public static boolean isConformantSchemeName(String p_scheme) {

        if (p_scheme == null || p_scheme.trim().length() == 0) {
            return false;
        }

        if (!isAlpha(p_scheme.charAt(0))) {
            return false;
        }

        char testChar;

        for (int i = 1; i < p_scheme.length(); i++) {
            testChar = p_scheme.charAt(i);

            if (!isAlphanum(testChar) && SCHEME_CHARACTERS.indexOf(testChar) == -1) {
                return false;
            }
        }

        return true;
    }

    /**
     * Determine whether a string is syntactically capable of representing
     * a valid IPv4 address or the domain name of a network host. A valid
     * IPv4 address consists of four decimal digit groups separated by a
     * '.'. A hostname consists of domain labels (each of which must
     * begin and end with an alphanumeric but may contain '-') separated
     * & by a '.'. See RFC 2396 Section 3.2.2.
     *
     * @param p_address The address string to check
     * @return true if the string is a syntactically valid IPv4 address
     * or hostname
     */
    public static boolean isWellFormedAddress(String p_address) {

        if (p_address == null) {
            return false;
        }

        String address    = p_address.trim();
        int    addrLength = address.length();

        if (addrLength == 0 || addrLength > 255) {
            return false;
        }

        if (address.startsWith(".") || address.startsWith("-")) {
            return false;
        }

        // rightmost domain label starting with digit indicates IP address
        // since top level domain label can only start with an alpha
        // see RFC 2396 Section 3.2.2
        int index = address.lastIndexOf('.');

        if (address.endsWith(".")) {
            index = address.substring(0, index).lastIndexOf('.');
        }

        if (index + 1 < addrLength && isDigit(p_address.charAt(index + 1))) {
            char testChar;
            int  numDots = 0;

            // make sure that 1) we see only digits and dot separators, 2) that
            // any dot separator is preceded and followed by a digit and
            // 3) that we find 3 dots
            for (int i = 0; i < addrLength; i++) {
                testChar = address.charAt(i);

                if (testChar == '.') {
                    if (!isDigit(address.charAt(i - 1))
                        || (i + 1 < addrLength && !isDigit(address.charAt(i + 1)))) {
                        return false;
                    }

                    numDots++;
                } else if (!isDigit(testChar)) {
                    return false;
                }
            }

            if (numDots != 3) {
                return false;
            }
        } else {

            // domain labels can contain alphanumerics and '-"
            // but must start and end with an alphanumeric
            char testChar;

            for (int i = 0; i < addrLength; i++) {
                testChar = address.charAt(i);

                if (testChar == '.') {
                    if (!isAlphanum(address.charAt(i - 1))) {
                        return false;
                    }

                    if (i + 1 < addrLength && !isAlphanum(address.charAt(i + 1))) {
                        return false;
                    }
                } else if (!isAlphanum(testChar) && testChar != '-') {
                    return false;
                }
            }
        }

        return true;
    }

    /**
     * Determine whether a char is a digit.
     *
     * @param p_char the character to check
     * @return true if the char is betweeen '0' and '9', false otherwise
     */
    private static boolean isDigit(char p_char) {
        return p_char >= '0' && p_char <= '9';
    }

    /**
     * Determine whether a character is a hexadecimal character.
     *
     * @param p_char the character to check
     * @return true if the char is betweeen '0' and '9', 'a' and 'f'
     * or 'A' and 'F', false otherwise
     */
    private static boolean isHex(char p_char) {
        return (isDigit(p_char) || (p_char >= 'a' && p_char <= 'f')
            || (p_char >= 'A' && p_char <= 'F'));
    }

    /**
     * Determine whether a char is an alphabetic character: a-z or A-Z
     *
     * @param p_char the character to check
     * @return true if the char is alphabetic, false otherwise
     */
    private static boolean isAlpha(char p_char) {
        return ((p_char >= 'a' && p_char <= 'z')
            || (p_char >= 'A' && p_char <= 'Z'));
    }

    /**
     * Determine whether a char is an alphanumeric: 0-9, a-z or A-Z
     *
     * @param p_char the character to check
     * @return true if the char is alphanumeric, false otherwise
     */
    private static boolean isAlphanum(char p_char) {
        return (isAlpha(p_char) || isDigit(p_char));
    }

    /**
     * Determine whether a character is a reserved character:
     * ';', '/', '?', ':', '@', '&', '=', '+', '$' or ','
     *
     * @param p_char the character to check
     * @return true if the string contains any reserved characters
     */
    private static boolean isReservedCharacter(char p_char) {
        return RESERVED_CHARACTERS.indexOf(p_char) != -1;
    }

    /**
     * Determine whether a char is an unreserved character.
     *
     * @param p_char the character to check
     * @return true if the char is unreserved, false otherwise
     */
    private static boolean isUnreservedCharacter(char p_char) {
        return (isAlphanum(p_char) || MARK_CHARACTERS.indexOf(p_char) != -1);
    }

    /**
     * Determine whether a given string contains only URI characters (also
     * called "uric" in RFC 2396). uric consist of all reserved
     * characters, unreserved characters and escaped characters.
     *
     * @param p_uric URI string
     * @return true if the string is comprised of uric, false otherwise
     */
    private static boolean isURIString(String p_uric) {

        if (p_uric == null) {
            return false;
        }

        int  end      = p_uric.length();
        char testChar = '\0';

        for (int i = 0; i < end; i++) {
            testChar = p_uric.charAt(i);

            if (testChar == '%') {
                if (i + 2 >= end || !isHex(p_uric.charAt(i + 1))
                    || !isHex(p_uric.charAt(i + 2))) {
                    return false;
                } else {
                    i += 2;

                    continue;
                }
            }

            if (isReservedCharacter(testChar) || isUnreservedCharacter(testChar)) {
                continue;
            } else {
                return false;
            }
        }

        return true;
    }

    /**
     * Initialize all fields of this URI from another URI.
     *
     * @param p_other the URI to copy (cannot be null)
     */
    private void initialize(URI p_other) {

        m_scheme = p_other.getScheme();
        m_userinfo = p_other.getUserinfo();
        m_host = p_other.getHost();
        m_port = p_other.getPort();
        m_path = p_other.getPath();
        m_queryString = p_other.getQueryString();
        m_fragment = p_other.getFragment();
    }

    /**
     * Initializes this URI from a base URI and a URI specification string.
     * See RFC 2396 Section 4 and Appendix B for specifications on parsing
     * the URI and Section 5 for specifications on resolving relative URIs
     * and relative paths.
     *
     * @param p_base    the base URI (may be null if p_uriSpec is an absolute
     *                  URI)
     * @param p_uriSpec the URI spec string which may be an absolute or
     *                  relative URI (can only be null/empty if p_base
     *                  is not null)
     * @throws MalformedURIException if p_base is null and p_uriSpec
     *                               is not an absolute URI or if
     *                               p_uriSpec violates syntax rules
     */
    private void initialize(URI p_base, String p_uriSpec)
        throws MalformedURIException {

        if (p_base == null
            && (p_uriSpec == null || p_uriSpec.trim().length() == 0)) {
            throw new MalformedURIException(
                XMLMessages.createXMLMessage(XMLErrorResources.ER_CANNOT_INIT_URI_EMPTY_PARMS, null)); //"Cannot initialize URI with empty parameters.");
        }

        // just make a copy of the base if spec is empty
        if (p_uriSpec == null || p_uriSpec.trim().length() == 0) {
            initialize(p_base);

            return;
        }

        String uriSpec    = p_uriSpec.trim();
        int    uriSpecLen = uriSpec.length();
        int    index      = 0;

        // check for scheme
        int colonIndex = uriSpec.indexOf(':');
        if (colonIndex < 0) {
            if (p_base == null) {
                throw new MalformedURIException(XMLMessages.createXMLMessage(XMLErrorResources.ER_NO_SCHEME_IN_URI, new Object[]{uriSpec})); //"No scheme found in URI: "+uriSpec);
            }
        } else {
            initializeScheme(uriSpec);
            uriSpec = uriSpec.substring(colonIndex + 1);
            // This is a fix for XALANJ-2059.
            if (m_scheme != null && p_base != null) {
                // a) If <uriSpec> starts with a slash (/), it means <uriSpec> is absolute
                //    and p_base can be ignored.
                //    For example,
                //    uriSpec = file:/myDIR/myXSLFile.xsl
                //    p_base = file:/myWork/
                //
                //    Here, uriSpec has absolute path after scheme file and :
                //    Hence p_base can be ignored.
                //
                // b) Similarily, according to RFC 2396, uri is resolved for <uriSpec> relative to <p_base>
                //    if scheme in <uriSpec> is same as scheme in <p_base>, else p_base can be ignored.
                //
                // c) if <p_base> is not hierarchical, it can be ignored.
                //
                if (uriSpec.startsWith("/") || !m_scheme.equals(p_base.m_scheme) || !p_base.getSchemeSpecificPart().startsWith("/")) {
                    p_base = null;
                }
            }
            // Fix for XALANJ-2059
            uriSpecLen = uriSpec.length();
        }

        // two slashes means generic URI syntax, so we get the authority
        if (uriSpec.startsWith("//")) {
            index += 2;

            int startPos = index;

            // get authority - everything up to path, query or fragment
            char testChar = '\0';

            while (index < uriSpecLen) {
                testChar = uriSpec.charAt(index);

                if (testChar == '/' || testChar == '?' || testChar == '#') {
                    break;
                }

                index++;
            }

            // if we found authority, parse it out, otherwise we set the
            // host to empty string
            if (index > startPos) {
                initializeAuthority(uriSpec.substring(startPos, index));
            } else {
                m_host = "";
            }
        }

        initializePath(uriSpec.substring(index));

        // Resolve relative URI to base URI - see RFC 2396 Section 5.2
        // In some cases, it might make more sense to throw an exception
        // (when scheme is specified is the string spec and the base URI
        // is also specified, for example), but we're just following the
        // RFC specifications
        if (p_base != null) {

            // check to see if this is the current doc - RFC 2396 5.2 #2
            // note that this is slightly different from the RFC spec in that
            // we don't include the check for query string being null
            // - this handles cases where the urispec is just a query
            // string or a fragment (e.g. "?y" or "#s") -
            // see <http://www.ics.uci.edu/~fielding/url/test1.html> which
            // identified this as a bug in the RFC
            if (m_path.length() == 0 && m_scheme == null && m_host == null) {
                m_scheme = p_base.getScheme();
                m_userinfo = p_base.getUserinfo();
                m_host = p_base.getHost();
                m_port = p_base.getPort();
                m_path = p_base.getPath();

                if (m_queryString == null) {
                    m_queryString = p_base.getQueryString();
                }

                return;
            }

            // check for scheme - RFC 2396 5.2 #3
            // if we found a scheme, it means absolute URI, so we're done
            if (m_scheme == null) {
                m_scheme = p_base.getScheme();
            }

            // check for authority - RFC 2396 5.2 #4
            // if we found a host, then we've got a network path, so we're done
            if (m_host == null) {
                m_userinfo = p_base.getUserinfo();
                m_host = p_base.getHost();
                m_port = p_base.getPort();
            } else {
                return;
            }

            // check for absolute path - RFC 2396 5.2 #5
            if (m_path.length() > 0 && m_path.startsWith("/")) {
                return;
            }

            // if we get to this point, we need to resolve relative path
            // RFC 2396 5.2 #6
            String path     = new String();
            String basePath = p_base.getPath();

            // 6a - get all but the last segment of the base URI path
            if (basePath != null) {
                int lastSlash = basePath.lastIndexOf('/');

                if (lastSlash != -1) {
                    path = basePath.substring(0, lastSlash + 1);
                }
            }

            // 6b - append the relative URI path
            path = path.concat(m_path);

            // 6c - remove all "./" where "." is a complete path segment
            index = -1;

            while ((index = path.indexOf("/./")) != -1) {
                path = path.substring(0, index + 1).concat(path.substring(index + 3));
            }

            // 6d - remove "." if path ends with "." as a complete path segment
            if (path.endsWith("/.")) {
                path = path.substring(0, path.length() - 1);
            }

            // 6e - remove all "<segment>/../" where "<segment>" is a complete
            // path segment not equal to ".."
            index = -1;

            int    segIndex   = -1;
            String tempString = null;

            while ((index = path.indexOf("/../")) > 0) {
                tempString = path.substring(0, path.indexOf("/../"));
                segIndex = tempString.lastIndexOf('/');

                if (segIndex != -1) {
                    if (!tempString.substring(segIndex++).equals("..")) {
                        path = path.substring(0, segIndex).concat(path.substring(index
                            + 4));
                    }
                }
            }

            // 6f - remove ending "<segment>/.." where "<segment>" is a
            // complete path segment
            if (path.endsWith("/..")) {
                tempString = path.substring(0, path.length() - 3);
                segIndex = tempString.lastIndexOf('/');

                if (segIndex != -1) {
                    path = path.substring(0, segIndex + 1);
                }
            }

            m_path = path;
        }
    }

    /**
     * Initialize the scheme for this URI from a URI string spec.
     *
     * @param p_uriSpec the URI specification (cannot be null)
     * @throws MalformedURIException if URI does not have a conformant
     *                               scheme
     */
    private void initializeScheme(String p_uriSpec) throws MalformedURIException {

        int    uriSpecLen = p_uriSpec.length();
        int    index      = 0;
        String scheme     = null;
        char   testChar   = '\0';

        while (index < uriSpecLen) {
            testChar = p_uriSpec.charAt(index);

            if (testChar == ':' || testChar == '/' || testChar == '?'
                || testChar == '#') {
                break;
            }

            index++;
        }

        scheme = p_uriSpec.substring(0, index);

        if (scheme.length() == 0) {
            throw new MalformedURIException(XMLMessages.createXMLMessage(XMLErrorResources.ER_NO_SCHEME_INURI, null)); //"No scheme found in URI.");
        } else {
            setScheme(scheme);
        }
    }

    /**
     * Initialize the authority (userinfo, host and port) for this
     * URI from a URI string spec.
     *
     * @param p_uriSpec the URI specification (cannot be null)
     * @throws MalformedURIException if p_uriSpec violates syntax rules
     */
    private void initializeAuthority(String p_uriSpec)
        throws MalformedURIException {

        int    index    = 0;
        int    start    = 0;
        int    end      = p_uriSpec.length();
        char   testChar = '\0';
        String userinfo = null;

        // userinfo is everything up @
        if (p_uriSpec.indexOf('@', start) != -1) {
            while (index < end) {
                testChar = p_uriSpec.charAt(index);

                if (testChar == '@') {
                    break;
                }

                index++;
            }

            userinfo = p_uriSpec.substring(start, index);

            index++;
        }

        // host is everything up to ':'
        String host = null;

        start = index;

        while (index < end) {
            testChar = p_uriSpec.charAt(index);

            if (testChar == ':') {
                break;
            }

            index++;
        }

        host = p_uriSpec.substring(start, index);

        int port = -1;

        if (host.length() > 0) {

            // port
            if (testChar == ':') {
                index++;

                start = index;

                while (index < end) {
                    index++;
                }

                String portStr = p_uriSpec.substring(start, index);

                if (portStr.length() > 0) {
                    for (int i = 0; i < portStr.length(); i++) {
                        if (!isDigit(portStr.charAt(i))) {
                            throw new MalformedURIException(
                                portStr + " is invalid. Port should only contain digits!");
                        }
                    }

                    try {
                        port = Integer.parseInt(portStr);
                    } catch (NumberFormatException nfe) {

                        // can't happen
                    }
                }
            }
        }

        setHost(host);
        setPort(port);
        setUserinfo(userinfo);
    }

    /**
     * Initialize the path for this URI from a URI string spec.
     *
     * @param p_uriSpec the URI specification (cannot be null)
     * @throws MalformedURIException if p_uriSpec violates syntax rules
     */
    private void initializePath(String p_uriSpec) throws MalformedURIException {

        if (p_uriSpec == null) {
            throw new MalformedURIException(
                "Cannot initialize path from null string!");
        }

        int  index    = 0;
        int  start    = 0;
        int  end      = p_uriSpec.length();
        char testChar = '\0';

        // path - everything up to query string or fragment
        while (index < end) {
            testChar = p_uriSpec.charAt(index);

            if (testChar == '?' || testChar == '#') {
                break;
            }

            // check for valid escape sequence
            if (testChar == '%') {
                if (index + 2 >= end || !isHex(p_uriSpec.charAt(index + 1))
                    || !isHex(p_uriSpec.charAt(index + 2))) {
                    throw new MalformedURIException(
                        XMLMessages.createXMLMessage(XMLErrorResources.ER_PATH_CONTAINS_INVALID_ESCAPE_SEQUENCE, null)); //"Path contains invalid escape sequence!");
                }
            } else if (!isReservedCharacter(testChar)
                && !isUnreservedCharacter(testChar)) {
                if ('\\' != testChar)
                    throw new MalformedURIException(XMLMessages.createXMLMessage(XMLErrorResources.ER_PATH_INVALID_CHAR, new Object[]{String.valueOf(testChar)})); //"Path contains invalid character: "
                //+ testChar);
            }

            index++;
        }

        m_path = p_uriSpec.substring(start, index);

        // query - starts with ? and up to fragment or end
        if (testChar == '?') {
            index++;

            start = index;

            while (index < end) {
                testChar = p_uriSpec.charAt(index);

                if (testChar == '#') {
                    break;
                }

                if (testChar == '%') {
                    if (index + 2 >= end || !isHex(p_uriSpec.charAt(index + 1))
                        || !isHex(p_uriSpec.charAt(index + 2))) {
                        throw new MalformedURIException(
                            "Query string contains invalid escape sequence!");
                    }
                } else if (!isReservedCharacter(testChar)
                    && !isUnreservedCharacter(testChar)) {
                    throw new MalformedURIException(
                        "Query string contains invalid character:" + testChar);
                }

                index++;
            }

            m_queryString = p_uriSpec.substring(start, index);
        }

        // fragment - starts with #
        if (testChar == '#') {
            index++;

            start = index;

            while (index < end) {
                testChar = p_uriSpec.charAt(index);

                if (testChar == '%') {
                    if (index + 2 >= end || !isHex(p_uriSpec.charAt(index + 1))
                        || !isHex(p_uriSpec.charAt(index + 2))) {
                        throw new MalformedURIException(
                            "Fragment contains invalid escape sequence!");
                    }
                } else if (!isReservedCharacter(testChar)
                    && !isUnreservedCharacter(testChar)) {
                    throw new MalformedURIException(
                        "Fragment contains invalid character:" + testChar);
                }

                index++;
            }

            m_fragment = p_uriSpec.substring(start, index);
        }
    }

    /**
     * Get the scheme for this URI.
     *
     * @return the scheme for this URI
     */
    public String getScheme() {
        return m_scheme;
    }

    /**
     * Set the scheme for this URI. The scheme is converted to lowercase
     * before it is set.
     *
     * @param p_scheme the scheme for this URI (cannot be null)
     * @throws MalformedURIException if p_scheme is not a conformant
     *                               scheme name
     */
    public void setScheme(String p_scheme) throws MalformedURIException {

        if (p_scheme == null) {
            throw new MalformedURIException(XMLMessages.createXMLMessage(XMLErrorResources.ER_SCHEME_FROM_NULL_STRING, null)); //"Cannot set scheme from null string!");
        }

        if (!isConformantSchemeName(p_scheme)) {
            throw new MalformedURIException(XMLMessages.createXMLMessage(XMLErrorResources.ER_SCHEME_NOT_CONFORMANT, null)); //"The scheme is not conformant.");
        }

        m_scheme = p_scheme.toLowerCase();
    }

    /**
     * Get the scheme-specific part for this URI (everything following the
     * scheme and the first colon). See RFC 2396 Section 5.2 for spec.
     *
     * @return the scheme-specific part for this URI
     */
    public String getSchemeSpecificPart() {

        StringBuffer schemespec = new StringBuffer();

        if (m_userinfo != null || m_host != null || m_port != -1) {
            schemespec.append("//");
        }

        if (m_userinfo != null) {
            schemespec.append(m_userinfo);
            schemespec.append('@');
        }

        if (m_host != null) {
            schemespec.append(m_host);
        }

        if (m_port != -1) {
            schemespec.append(':');
            schemespec.append(m_port);
        }

        if (m_path != null) {
            schemespec.append((m_path));
        }

        if (m_queryString != null) {
            schemespec.append('?');
            schemespec.append(m_queryString);
        }

        if (m_fragment != null) {
            schemespec.append('#');
            schemespec.append(m_fragment);
        }

        return schemespec.toString();
    }

    /**
     * Get the userinfo for this URI.
     *
     * @return the userinfo for this URI (null if not specified).
     */
    public String getUserinfo() {
        return m_userinfo;
    }

    /**
     * Set the userinfo for this URI. If a non-null value is passed in and
     * the host value is null, then an exception is thrown.
     *
     * @param p_userinfo the userinfo for this URI
     * @throws MalformedURIException if p_userinfo contains invalid
     *                               characters
     */
    public void setUserinfo(String p_userinfo) throws MalformedURIException {

        if (p_userinfo == null) {
            m_userinfo = null;
        } else {
            if (m_host == null) {
                throw new MalformedURIException(
                    "Userinfo cannot be set when host is null!");
            }

            // userinfo can contain alphanumerics, mark characters, escaped
            // and ';',':','&','=','+','$',','
            int  index    = 0;
            int  end      = p_userinfo.length();
            char testChar = '\0';

            while (index < end) {
                testChar = p_userinfo.charAt(index);

                if (testChar == '%') {
                    if (index + 2 >= end || !isHex(p_userinfo.charAt(index + 1))
                        || !isHex(p_userinfo.charAt(index + 2))) {
                        throw new MalformedURIException(
                            "Userinfo contains invalid escape sequence!");
                    }
                } else if (!isUnreservedCharacter(testChar)
                    && USERINFO_CHARACTERS.indexOf(testChar) == -1) {
                    throw new MalformedURIException(
                        "Userinfo contains invalid character:" + testChar);
                }

                index++;
            }
        }

        m_userinfo = p_userinfo;
    }

    /**
     * Get the host for this URI.
     *
     * @return the host for this URI (null if not specified).
     */
    public String getHost() {
        return m_host;
    }

    /**
     * Set the host for this URI. If null is passed in, the userinfo
     * field is also set to null and the port is set to -1.
     *
     * @param p_host the host for this URI
     * @throws MalformedURIException if p_host is not a valid IP
     *                               address or DNS hostname.
     */
    public void setHost(String p_host) throws MalformedURIException {

        if (p_host == null || p_host.trim().length() == 0) {
            m_host = p_host;
            m_userinfo = null;
            m_port = -1;
        } else if (!isWellFormedAddress(p_host)) {
            throw new MalformedURIException(XMLMessages.createXMLMessage(XMLErrorResources.ER_HOST_ADDRESS_NOT_WELLFORMED, null)); //"Host is not a well formed address!");
        }

        m_host = p_host;
    }

    /**
     * Get the port for this URI.
     *
     * @return the port for this URI (-1 if not specified).
     */
    public int getPort() {
        return m_port;
    }

    /**
     * Set the port for this URI. -1 is used to indicate that the port is
     * not specified, otherwise valid port numbers are  between 0 and 65535.
     * If a valid port number is passed in and the host field is null,
     * an exception is thrown.
     *
     * @param p_port the port number for this URI
     * @throws MalformedURIException if p_port is not -1 and not a
     *                               valid port number
     */
    public void setPort(int p_port) throws MalformedURIException {

        if (p_port >= 0 && p_port <= 65535) {
            if (m_host == null) {
                throw new MalformedURIException(
                    XMLMessages.createXMLMessage(XMLErrorResources.ER_PORT_WHEN_HOST_NULL, null)); //"Port cannot be set when host is null!");
            }
        } else if (p_port != -1) {
            throw new MalformedURIException(XMLMessages.createXMLMessage(XMLErrorResources.ER_INVALID_PORT, null)); //"Invalid port number!");
        }

        m_port = p_port;
    }

    /**
     * Get the path for this URI (optionally with the query string and
     * fragment).
     *
     * @param p_includeQueryString if true (and query string is not null),
     *                             then a "?" followed by the query string
     *                             will be appended
     * @param p_includeFragment    if true (and fragment is not null),
     *                             then a "#" followed by the fragment
     *                             will be appended
     * @return the path for this URI possibly including the query string
     * and fragment
     */
    public String getPath(boolean p_includeQueryString,
                          boolean p_includeFragment) {

        StringBuffer pathString = new StringBuffer(m_path);

        if (p_includeQueryString && m_queryString != null) {
            pathString.append('?');
            pathString.append(m_queryString);
        }

        if (p_includeFragment && m_fragment != null) {
            pathString.append('#');
            pathString.append(m_fragment);
        }

        return pathString.toString();
    }

    /**
     * Get the path for this URI. Note that the value returned is the path
     * only and does not include the query string or fragment.
     *
     * @return the path for this URI.
     */
    public String getPath() {
        return m_path;
    }

    /**
     * Set the path for this URI. If the supplied path is null, then the
     * query string and fragment are set to null as well. If the supplied
     * path includes a query string and/or fragment, these fields will be
     * parsed and set as well. Note that, for URIs following the "generic
     * URI" syntax, the path specified should start with a slash.
     * For URIs that do not follow the generic URI syntax, this method
     * sets the scheme-specific part.
     *
     * @param p_path the path for this URI (may be null)
     * @throws MalformedURIException if p_path contains invalid
     *                               characters
     */
    public void setPath(String p_path) throws MalformedURIException {

        if (p_path == null) {
            m_path = null;
            m_queryString = null;
            m_fragment = null;
        } else {
            initializePath(p_path);
        }
    }

    /**
     * Get the query string for this URI.
     *
     * @return the query string for this URI. Null is returned if there
     * was no "?" in the URI spec, empty string if there was a
     * "?" but no query string following it.
     */
    public String getQueryString() {
        return m_queryString;
    }

    /**
     * Set the query string for this URI. A non-null value is valid only
     * if this is an URI conforming to the generic URI syntax and
     * the path value is not null.
     *
     * @param p_queryString the query string for this URI
     * @throws MalformedURIException if p_queryString is not null and this
     *                               URI does not conform to the generic
     *                               URI syntax or if the path is null
     */
    public void setQueryString(String p_queryString)
        throws MalformedURIException {

        if (p_queryString == null) {
            m_queryString = null;
        } else if (!isGenericURI()) {
            throw new MalformedURIException(
                "Query string can only be set for a generic URI!");
        } else if (getPath() == null) {
            throw new MalformedURIException(
                "Query string cannot be set when path is null!");
        } else if (!isURIString(p_queryString)) {
            throw new MalformedURIException(
                "Query string contains invalid character!");
        } else {
            m_queryString = p_queryString;
        }
    }

    /**
     * Get the fragment for this URI.
     *
     * @return the fragment for this URI. Null is returned if there
     * was no "#" in the URI spec, empty string if there was a
     * "#" but no fragment following it.
     */
    public String getFragment() {
        return m_fragment;
    }

    /**
     * Set the fragment for this URI. A non-null value is valid only
     * if this is a URI conforming to the generic URI syntax and
     * the path value is not null.
     *
     * @param p_fragment the fragment for this URI
     * @throws MalformedURIException if p_fragment is not null and this
     *                               URI does not conform to the generic
     *                               URI syntax or if the path is null
     */
    public void setFragment(String p_fragment) throws MalformedURIException {

        if (p_fragment == null) {
            m_fragment = null;
        } else if (!isGenericURI()) {
            throw new MalformedURIException(
                XMLMessages.createXMLMessage(XMLErrorResources.ER_FRAG_FOR_GENERIC_URI, null)); //"Fragment can only be set for a generic URI!");
        } else if (getPath() == null) {
            throw new MalformedURIException(
                XMLMessages.createXMLMessage(XMLErrorResources.ER_FRAG_WHEN_PATH_NULL, null)); //"Fragment cannot be set when path is null!");
        } else if (!isURIString(p_fragment)) {
            throw new MalformedURIException(XMLMessages.createXMLMessage(XMLErrorResources.ER_FRAG_INVALID_CHAR, null)); //"Fragment contains invalid character!");
        } else {
            m_fragment = p_fragment;
        }
    }

    /**
     * Append to the end of the path of this URI. If the current path does
     * not end in a slash and the path to be appended does not begin with
     * a slash, a slash will be appended to the current path before the
     * new segment is added. Also, if the current path ends in a slash
     * and the new segment begins with a slash, the extra slash will be
     * removed before the new segment is appended.
     *
     * @param p_addToPath the new segment to be added to the current path
     * @throws MalformedURIException if p_addToPath contains syntax
     *                               errors
     */
    public void appendPath(String p_addToPath) throws MalformedURIException {

        if (p_addToPath == null || p_addToPath.trim().length() == 0) {
            return;
        }

        if (!isURIString(p_addToPath)) {
            throw new MalformedURIException(XMLMessages.createXMLMessage(XMLErrorResources.ER_PATH_INVALID_CHAR, new Object[]{p_addToPath})); //"Path contains invalid character!");
        }

        if (m_path == null || m_path.trim().length() == 0) {
            if (p_addToPath.startsWith("/")) {
                m_path = p_addToPath;
            } else {
                m_path = "/" + p_addToPath;
            }
        } else if (m_path.endsWith("/")) {
            if (p_addToPath.startsWith("/")) {
                m_path = m_path.concat(p_addToPath.substring(1));
            } else {
                m_path = m_path.concat(p_addToPath);
            }
        } else {
            if (p_addToPath.startsWith("/")) {
                m_path = m_path.concat(p_addToPath);
            } else {
                m_path = m_path.concat("/" + p_addToPath);
            }
        }
    }

    /**
     * Determines if the passed-in Object is equivalent to this URI.
     *
     * @param p_test the Object to test for equality.
     * @return true if p_test is a URI with all values equal to this
     * URI, false otherwise
     */
    public boolean equals(Object p_test) {

        if (p_test instanceof URI) {
            URI testURI = (URI) p_test;

            if (((m_scheme == null && testURI.m_scheme == null) || (m_scheme != null && testURI.m_scheme != null && m_scheme.equals(
                testURI.m_scheme))) && ((m_userinfo == null && testURI.m_userinfo == null) || (m_userinfo != null && testURI.m_userinfo != null && m_userinfo.equals(
                testURI.m_userinfo))) && ((m_host == null && testURI.m_host == null) || (m_host != null && testURI.m_host != null && m_host.equals(
                testURI.m_host))) && m_port == testURI.m_port && ((m_path == null && testURI.m_path == null) || (m_path != null && testURI.m_path != null && m_path.equals(
                testURI.m_path))) && ((m_queryString == null && testURI.m_queryString == null) || (m_queryString != null && testURI.m_queryString != null && m_queryString.equals(
                testURI.m_queryString))) && ((m_fragment == null && testURI.m_fragment == null) || (m_fragment != null && testURI.m_fragment != null && m_fragment.equals(
                testURI.m_fragment)))) {
                return true;
            }
        }

        return false;
    }

    /**
     * Get the URI as a string specification. See RFC 2396 Section 5.2.
     *
     * @return the URI string specification
     */
    public String toString() {

        StringBuffer uriSpecString = new StringBuffer();

        if (m_scheme != null) {
            uriSpecString.append(m_scheme);
            uriSpecString.append(':');
        }

        uriSpecString.append(getSchemeSpecificPart());

        return uriSpecString.toString();
    }

    /**
     * Get the indicator as to whether this URI uses the "generic URI"
     * syntax.
     *
     * @return true if this URI uses the "generic URI" syntax, false
     * otherwise
     */
    public boolean isGenericURI() {

        // presence of the host (whether valid or empty) means
        // double-slashes which means generic uri
        return (m_host != null);
    }

    /**
     * MalformedURIExceptions are thrown in the process of building a URI
     * or setting fields on a URI when an operation would result in an
     * invalid URI specification.
     */
    public static class MalformedURIException extends IOException {

        /**
         * Constructs a <code>MalformedURIException</code> with no specified
         * detail message.
         */
        public MalformedURIException() {
            super();
        }

        /**
         * Constructs a <code>MalformedURIException</code> with the
         * specified detail message.
         *
         * @param p_msg the detail message.
         */
        public MalformedURIException(String p_msg) {
            super(p_msg);
        }
    }
}
